The Denver Broncos have fired offensive coordinator Mike McCoy and are replacing him with quarterbacks coach Bill Musgrave.

Klint Kubiak will take over as QBs coach while Musgrave calls plays for the final six weeks of a soured season that began with promise. The Broncos are mired in their longest losing streak in a single season since 1990.

“I have a responsibility to do what’s best for our football team,” coach Vance Joseph said in a statement ahead of his Monday news conference.

“Although this wasn’t an easy decision, we needed to make this change. We have to play a more efficient brand of football offensively as we begin the final stretch of our season.”

The Broncos (3-7) are mired in a six-game skid, and McCoy had increasingly drawn scrutiny for his overly complex game plans and insistence on using three wide receivers as his base formation to both pass and run, even though the vast majority of the Broncos’ penalties, sacks and turnovers have come out of that formation.

McCoy said in a statement released by the team that he was disappointed his second stint as Denver’s offensive architect went poorly “because this is a special organization and a great place to be.”

Musgrave, who was general manager John Elway’s backup quarterback in Denver in the late 1990s, is a 20-year coaching veteran with nine NFL seasons as an offensive coordinator with the Raiders, Vikings, Jaguars, Panthers and Eagles.

The changes could be a precursor to giving former first-round draft pick Paxton Lynch an audition at quarterback.

Elway moved up in the 2016 draft to select Lynch with the 26th pick, but the former Memphis star was beaten out by Trevor Siemian two summers in a row.

Siemian was benched three weeks ago in favor of Brock Osweiler.

Lynch spent the first two months of the season recovering from a sprained shoulder he sustained in the preseason and he was active Sunday for the first time, although he appeared disengaged during the Broncos’ 20-17 loss to the Cincinnati Bengals .

It was originally believed that if he helped guide the Broncos back to the playoffs, McCoy’s stint could be short, as he’d be a hot candidate for the next coaching carrousel.

Instead, he lasted just 10 games.

Whether it was Siemian or Osweiler starting, McCoy produced game plans as though Peyton Manning were still Denver’s signal-caller.

McCoy was recently instructed to simplify things, but he continued to rely heavily on “11 personnel,” the NFL’s vernacular for one running back, one tight end and three wide receivers.

He did that despite an offensive line struggling with pass rushers and beset by injuries.

Plus, the Broncos don’t have a slot receiver that scares defenses, and their tight end group is one of the worst in the league.

McCoy’s first stint in Denver was much more successful. He scrapped an offense midseason for Tim Tebow in 2011 and the following season helped Manning transition to his new team as he began a spectacularly successful comeback following neck fusion surgery.